Snagging device for inverted grinder

ABSTRACT

Improved inverted pump/grinder construction is presented herein. At least one sharp-edged protrusion is located below the impeller/shredder zone to interrupt the spinning motion of objects, which tend to become entangled on the impeller. This interruption by the protrusion renders such objects more readily subjected to the impeller/shredder action and thereby prevents formation of a large tangled mass.

United States Patent Farrell, Jr. 1

[ 1 SNAGGING DEVICE FOR INVERTED GRINDER [72] Inventor: Robert P. Farrell, Jr., Schenectady,

The United States 01 America as represented by the Secretary of the Interior Filed: Sept. 1, 1970 Appl. No.: 68,691

Assignee:

U.S. Cl ..24l/46.l1 Int. Cl. 18/06 Field o1Search.....24l/46.02, 46.11, 46.17, 258,

[56] References Cited UNITED STATES PATENTS 9/1958 7 Wilder....,, ...,241[46.11 x

Us] 3,701,486 [4 1 Oct-31, 1972 2,573,129 10/1951 Dulait ..24l/275 X 2,848,172 3/1958 Ewing ..24l/46.11 X 3,128,051 4/1964 Smith ..241/46.1l

Primary Examiner-Granville Y. Custer, Jr. Attorney-Ernest S. Cohen and Benjamin H. Bochenek [57] ABSTRACT Improved inverted pump/grinder construction is presented herein. At least one sharp-edged protrusion is located below the impeller/shredder zone to interrupt the spinning motion of objects, which tend to become entangled on the impeller. This interruption by the protrusion renders such objects more readily subjected to the impeller/shredder action and thereby prevents-formation of a large tangled mass.

2 Claims, 2 Drawing Figures PATENTEDBBTIH m2 3,701,486

/MPELLE R074 TIO/V m/ VEW TOR.- RUBERT P FARRELL, Jr.

H/S ATTORNEY SNAGGING DEVICE FORJNVERTED. GRINDER The invention herein described was madein the course of or under a contract with the United States Department of Interior.

BACKGROUND OF THE INVENTION 1.U.S. Pat. No. .3',366,339, Fair is directed to a-system for the separate transport of sanitary sewage and storm water, utilizing'a pressurized system for transport of the sanitary sewage. The term sanitarysewage is used to 1 designate waterdischargedfrom sanitary fixtures and collected .as wastewater afterserving its primary purpose, aswell as water servingthe purpose of carrying away other waste matter from households, mercantile, commercial and industrial establishments.

According to the concept intheFairpatent sanitary sewage would be intercepted in individual buildings,

from whichit would be pumped into pressurized street sewers. Because rather small sized tubing and piping would be required'for transmitting sewage, a reduction in particle size of much of the solid matter encountered in sanitary sewage is necessary prior to pumping such material from individual buildings into the street sewage lines The most practical method proposed for the reduction in particle size isby means of grinding,

shredding or combined grinding and shredding.

The most practical construction is effected by mounting the grinder in an upside-downpositionin a holding tank and providing a relatively largeaccess opening into the grinding region what the velocityof sanitary sewage enteringthe grinderewillbe sufficiently low that particles of glass or-rnetal will settle to'thebottom of the holding tank andnotdamagethe-grinder or settle in (and impedeflow ini),thehi gh pressure effluent t input to the grinder motor wasnearly ten times the nor- ('45 mal level. In order to satisfactorily overcome such high levels of viscous drag an increase in the horsepower of the grinder motor would have been necessary to the extent that normal household circuits would not be adequate to supply the required power (e.g., ll Vzhp or greater).

SUMMARY OF THE INVENTION impeller/shredder zone to interrupt the spinning motion of any materials being dragged by the impeller to render such materials more readily subject to the impeller/shredder action and thereby prevent the formation of large tangled masses.

BRIEF DESCRIPTION OF THE DRAWING The exact nature of this invention as well as the objects and advantages thereof will be readily apparent 2 from consideration of the following specification relating to the annexed drawing, wherein:

FIG. .1 is a vertical view partly in section showing the interrelated construction of the grinding mechanism,

drive motor and pumping mechanism and, in combina- .tion therewith, a ring-shaped device constituting an embodiment of the instant invention and FIG. 2 is a plan view of the ring configuration shown embodied in the structure of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT lnFlG. lthe combined pump/grinder mechanism is shown affixed to mounting flange 11 to facilitate disposition of .the grinder mechanism within a storage tank (not shown). Motor 12 simultaneously drives iflywheel l3"(via shaft 14) and pump 16 (via belt drive 17-).

Cylindrical housing .18 encloses both shaft 14 and delivery tube-.19 leading from suction zone 21 (above flywheel l3):tothe-inlet of pump .16. Level control 7 means (not shown) are employedlto energize a thermal time delayrelay (not shown) which in turn operates switching means for motor 12. The thermal relay is employed to provide a predictable delay in both on and off switching functions. Such systems are'widely employed as level controllers in modern day automatic clothes washers and dishwashers. Bearing/seal assembly 22 prevents liquid from entering housing 18 along shaft 14.,

Flywheel '13 affixed to the lowerendof shaft 14 is made with a streamlined configuration to minimize viscous drag thereon as it isrotated in the surrounding liquid and impellers 23 are rigidly affixed thereto or formed thereon. Grinding and shredding functions are provided through the interaction of impellers 23 and shredder ring .24having lugs 26 of various shapes and projecting a short distance from the shredder ring 24.

Itwas determined bytest that selection of the motor speed had a very significant effect on the viscous drag encountered in operation of the unit. Thus, by reducing motor speed from 3,450 rpm to 1,725 rpm the viscous drag was reducedby at least 85 percentand by providing a streamlined flywheel, the viscous drag was further 'reducedby at least a third.

In testing it was found, however, that when certain classes of foreign objects were introduced into the inverted grinder as heretofore described and operated, these objects almost inevitably became entangled under the lip of an impeller and were simply pulled through the water by the impeller and evaded the shredder/impeller action. Thus, objects such as strings, bits of cloth, rubber and the like in becoming so entangled with the impeller gradually became more tightly twisted, knotted and entangled with each other until they formed unmanageable masses. The dragging of such an unmanageable mass through the water greatly increased the viscous drag and would have increased the required motor horsepower. In fact, the horsepower demands for such a system would have increased to the point at which normal volt) household circuits would not be adequate to supply the necessary power (e.g., l ,6 hp or higher).

It was found that by introducing; at least one sharpedged protrusion, or snagging means, immediately below the impeller/shredder zone extending inwardly, the spinning motion of materials entangled with the impeller is stopped long enough by such a protrusion to permit the normal upwardly directed low velocity water flow to carry such materials into the cutting/shredding region before there is a chance to develop a large tangled mass.

Although the requisite protrusion, or snagging means, to interrupt the constant rotation of entangled material may be cast or otherwise made an integral part of shredder ring 24 at some position below lugs 26, a convenient way for the introduction of such a protrusion is by means of a separate piece in the form of a ring having the desired number of protrusions in the desired configurations. Ring 27 inserted in the vertical clearance between shredder ring 24 and suction bell 28 presents four protrusions 29, 31, 32 and 33. In any construction employing a single or multiple protrusions one protrusion e.g. protrusion 29 constitutes the snagging means and should be large enough to'project radially inwardly toward the shaft axis further than lugs 26 and any other protrusions thereby functioning to snag string, fabric, rubber, etc., that might become entangled on one or more impellers.

If desired, each of the other protrusions employed may be made in identical shape or (as in the case of protrusion 31) may be in the form of a hook-shaped tooth. Whether or not any tooth configuration is employed all protrusions must have sharp leading edges in order to provide a slashing action. The disposition of the leading edges of the protrusions relative to the direction of rotation of the impeller must be as is shown in FIG. 2. r

The protrusions themselves should be made of some hardened material such as 410 stainless steel hardened to 35-5 Rockwell C, tungsten carbide or similar material able to provide a durable sharp leading edge. If the protrusions are provided as inserts in ring 27, ring 27 itself may be made of any strong, corrosion-resistant material, since it would only position the protrusions relative to the impeller/shredder zone.

By providing and properly locating the sharp-edged snagging means of this invention the development of tightly twisted knotted masses dragged by one or both impellers is prevented and the utilization of a smaller horsepower motor is made possible.

Mounting flange 11, flywheel 13, shaft 14, delivery tube 19, bearing/seal assembly 22, impellers 23, shredder ring 24 and suction bell 28 are made of conventional materials for the requisite performance required thereof.

What I claim as new and desire to secure by Letters Patent of the United States is: I

1. In an apparatus for the grinding/shredding of solid materials contained in a liquid flow and the pumping of the resulting mixture under pressure wherein the grinding/shredding action is accomplished by the interaction of flywheel-mounted impellers and a stationary shredder ring, the flywheel being mounted on a vertically-disposed shaft and the shaft depending from the drive means therefor, the liquid flow entering the impeller/shredder zone from below and being pumped away from above the impeller/shredder zone, the improvement com rising:

a. a single sta ionary snagg ng means mounted below the impeller/shredder zone for snagging material entangled on and dragged by one or more impellers, said snagging means comprising annular means underlying said shredder ring and having an inwardly extending tooth-like projection presenting a sharp leading edge transverse to the direction of liquid flow, said projection being disposed closer to the shaft axis than any portion of said shredder ring.

2. The improvement recited in claim 1 wherein said annular means includes a plurality of additional inwardly extending tooth-like projections, each of which has a sharp leading ledge that is transverse to the direction of liquid flow, said additional projections extending a lesser distance inwardly toward said shaft axis than said first named tooth-like projection. 

1. In an apparatus for the grinding/shredding of solid materials contained in a liquid flow and the pumping of the resulting mixture under pressure wherein the grinding/shredding action is accomplished by the interaction of flywheel-mounted impellers and a stationary shredder ring, the flywheel being mounted on a vertically-disposed shaft and the shaft depending from the drive means therefor, the liquid flow entering the impeller/shredder zone from below and being pumped away from above the impeller/shredder zone, the improvement comprising: a. a single stationary snagging means mounted below the impeller/shredder zone for snagging material entangled on and dragged by one or more impellers, said snagging means comprising annular means underlying said shredder ring and having an inwardly extending tooth-like projection presenting a sharp leading edge transverse to the direction of liquid flow, said projection being disposed closer to the shaft axis than any portion of said shredder ring.
 2. The improvement recited in claim 1 wherein said annular means includes a plurality of additional inwardly extending tooth-like projections, each of which has a sharp leading ledge that is transverse to the direction of liquid flow, said additional projections extending a lesser distance inwardly toward said shaft axis than said first named tooth-like projection. 